This disclosure relates generally to hydraulic power units. More particularly, this disclosure relates to portable hydraulic power units.
Hydraulic power units drive hydraulic fluid to a hydraulically-driven tool under pressure to cause the hydraulically-driven tool to perform work. Hydraulic power units include multiple pumps that pump the hydraulic fluid through a hydraulic circuit to the hydraulically-driven tool. The pumps are typically plunger pumps that are submerged in the hydraulic fluid in a fluid tank of the hydraulic power unit. The pumps also include georotor pumps submerged in the hydraulic fluid for high-flow applications. The in-tank pumps are exposed to hydraulic fluid on both an interior and an exterior of the pumps. To build sufficiently high pressure to drive the hydraulically-driven tool, the hydraulic power unit utilizes staged approach. Each stage is relieved by a spring-loaded relief valve when that stages maximum pressure is achieved.
A lid enclosed the fluid tank, and a long gasket with a geometry matching the geometry of the top of the fluid tank is disposed between the lid and the fluid tank to prevent contaminants from entering the fluid tank. To service an in-tank pump, the user removes the lid, which can expose the hydraulic fluid to contamination, and retrieves the in-tank pump from the hydraulic fluid. In addition, the fluid tank can be mounted below the other systems on the hydraulic power unit, such that the user is required to remove the other systems prior to accessing the tank. When returning the hydraulic power unit to service, the user is required to properly seat the long gasket between the fluid tank and the lid to prevent leakage.